Elevated plus maze as an animal model of state anxiety in Kunming mice:test-retest reliability

Abstract

Objective To explore the test-retest reliability of elevated plus maze (EPM) which is taken as an animal model of state anxiety in Kunming mice. Methods The behavior of adult, male and female, Kunming mice in EPM was recorded twice with one-week inter-trial interval for lasting five minutes.The following parameters were evaluated: percentage of time on EPM open arms (Otime%), percentage of time on EPM closed arms (Ctime%), time on EPM open arms (Otime), time on EPM closed arms (Ctime), percentage of entries into EPM open arms (Oentries%), entries into EPM open arms (Oentries), entries into EPM closed arms (Centries), total entries into EPM open and closed arms (Entries). Subsequently, the intraclass correlation coefficient (ICC) and the kappa agreement index (κ) were calculated for these parameters. Results ICC for Otime% (♂ ICC=0.506, P<0.05; ♀ ICC=0.456, P<0.05; ♂+ ♀ ICC=0.492, P<0.01), Oentries (♂ ICC=0.673, P<0.01; ♀ ICC=0.648, P<0.01; ♂+ ♀ ICC=0.665, P<0.01), Centries (♂ ICC=0.704, P<0.01; ♀ ICC=0.661, P<0.01; ♂+ ♀ ICC=0.686, P<0.01), Entries (♂ ICC=0.701, P<0.01; ♀ ICC=0.661, P<0.01; ♂+ ♀ ICC=0.685, P<0.01) showed a fair test-retest reliability, respectively. Only κ for Entries (♂ κ=0.253, P<0.05; ♀ κ=0.339, P<0.05; ♂+ ♀ κ=0.298, P<0.01) displayed a significant but poor reliability between the test-retest trials. Conclusion The Otime% Entries parameters as an acceptable index for Kunming mice in EPM can be used for exploratory and locomotion activity. Sex and repeated measurement have different effects on the Otime% and Entries parameters, especially the more on the former. Therefore, Otime% and Entries can be considered when EPM as an animal model of state anxiety in Kunming mice; meanwhile, more attention should be paid to both the sex (male animals recommended to EPM, especially) and repeated measurement effects. Key words: Elevated plus maze; State anxiety; Animal model; Test-retest reliability; Sex; Repeated measurement; Kunming mice